1. Field of the Invention
This invention relates to environmental stressing of electrical components and more specifically to thermal or burn-in stressing of microelectronic components including integrated circuit components, such as dual in-line packages (DIP), and associated electrical testing of the components.
2. Description of the Prior Art
Temperature accelerated heat aging to determine the performance of electrical components over their life expectancy is almost universally employed. Not only is such testing used during the development of new products, but many electrical components are subjected to some form of environmental thermal testing prior to shipment. Indeed such thermal cycling is often a part of the manufacturing process. For example, thermal or burn-in procedures are conducted to qualify integrated circuits and integrated circuit components. Conventional techniques for manufacturing integrated circuits do not have a 100% yield. Furthermore, packaging of integrated circuit components also yields a certain percentage of unsatisfactory components. Burn-in testing is one conventional method in which unsatisfactory components are identified.
One common burn-in test standard defines the purpose of such procedures as follows:
"The burn-in test is performed for the purpose of screening or eliminating marginal devices, those with inherent defects or defects resulting from manufacturing aberrations which cause time and stress dependent failures. In the absence of burn-in, these defective devices would be expected to result in infant mortality or early lifetime failure under use conditions. Therefore, it is the intent of this screen to stress microcircuits at or above maximum rated operating conditions or to apply equivalent screening conditions which will reveal time and stress dependent failure modes with equal or greater sensitivity."Mil-Std-883C, Method 1015.5, Aug. 25, 1983.
Conventional burn-in procedures employ relatively large expensive burn-in ovens into which a multitude of microelectronic, microcircuit or integrated circuit components, such as dual in-line packages, are introduced. As the temperature in the oven is elevated, the component is stressed, and the integrated circuit components can be energized by test signals during or after the heating, and their relative performance is monitored to identify unsatisfactory components. Components, such as dual in-line packages (DIP's) can be introduced into the burn-in ovens by first inserting the integrated circuit components into high temperature burn-in sockets. One conventional socket that is suitable for use in burn-in applications for DIPs is the DIPLOMATE HT socket manufactured by AMP Incorporated. DIPLOMATE is a registered trademark of AMP Incorporated. These sockets can be inserted into a printed circuit board and soldered to the board. For burn-in applications, a large number of such sockets are often employed.
When used in conventional burn-in ovens or constant temperature chambers, the integrated circuit components mounted in burn-in sockets soldered to the printed circuit boards are positioned on racks in the burn-in oven. It will be appreciated that such burn-in ovens must be relatively complex, when it is appreciated that precise temperature regulation throughout the high temperature chamber must be controlled even in the presence of the large number of printed circuit board mounted components. Not only must the steady state temperature be precisely controlled, but the heating and cooldown times must be properly regulated.
Conventionally each printed circuit board positioned within the burn-in oven is interconnected to an edge card connector, also located within the high temperature section of the burn-in oven. Edge card connectors normally employed within burn-in ovens must be of the high performance type capable of repeated performance at the test conditions and over the test range in the burn-in oven. These card edge connectors are in turn connected to the exterior of the burn-in oven and to a test signal driving circuit capable of generating signals to operate and evaluate the components to be tested. These driving circuits are in turn driven by electrical power sources located on the exterior of the high temperature chamber, or high temperature section of the burn-in oven. Integrated circuit components mounted within the high temperature section of the burn-in oven are then subjected to an elevated temperature for a specified period. Standard test specifications designating the minimum test time at a given temperature are employed. One example is Mil-Std 883c Method 1015.5. It will be appreciated that such conventional burn-in testing can be a relatively complex and expensive procedure employing not only expensive burn-in equipment but also expensive sockets and connectors for use in high temperature burn-in ovens.
The instant invention constitutes a simple, less costly, alternative which eliminates the need for the high temperature burn-in ovens now employed. The instant invention is not only adaptable to large scale burn-in testing for a large number of components in which automated assembly or robotic assembly is employed to mount the components for burn-in testing, but is also suitable for use in small scale applications such as in development testing of such products.